The present invention relates to an electromagnetic relay apparatus structured by using a plurality of electromagnetic blocks such as a twin type electromagnetic relay.
There have been utilized electromagnetic relay apparatuses, which comprise a plurality of electromagnetic relays being connected one to another. The electromagnetic relay comprised in the apparatus as a block unit is a switch for opening and closing electric contacts for carrying out inversion control (forward/backward direction control) of a motor or solenoid.
For example, the electromagnetic relay apparatus is adopted for automobiles. Recent automobiles are increasingly equipped with various electrical devices as the result of advances in the miniaturization, high-density mounting and cost reduction of the devices. In other words, the high adoption rate of electrical devices in automobiles can be achieved through development or improvement in the installed devices. Consequently, the electromagnetic relay apparatus requires more miniaturization, cost reduction as well as improvement in reliability, the accuracy of parts assembly, and productivity etc. in the market.
Among such electromagnetic relay apparatuses, there has been disclosed an electromagnetic relay in Japanese Patent Application laid open No. 2000-315448. The electromagnetic relay comprises plural electromagnetic blocks each having two moving contacts that swing up and down by the excitation current flow in a coil, a first stationary terminal having plural first stationary contacts each aligned with respective moving contacts, and a second stationary terminal having plural second stationary contacts each aligned with respective moving contacts.
Each electromagnetic block is provided with a couple of coil terminals each having an end connected to external wiring. The electromagnetic blocks are uniformly oriented and aligned in line. The first stationary terminal has an end connected to external wiring, and is set so that the first stationary contacts are located above the moving contacts. The second stationary terminal also has an end connected to external wiring. The second stationary terminal is set in an orthogonal direction of the arrangement of the electromagnetic blocks in such a manner that the second stationary contacts are located under the moving contacts.
The moving contact is magnetically attracted to the coil and comes in contact with the second stationary contact when current is applied to the coil. When current is not passed through the coil, the moving contact is in contact with the first stationary contact. Accordingly, desired circuits can be opened or closed through respective connecting ends of electromagnetic blocks as well as at the connecting ends of the first and second stationary terminals.
The electromagnetic relay, however, has some problems due to its construction in which uniformly oriented electromagnetic blocks are integrally coupled in aligned and parallel relation, and share the same first and second stationary terminals.
First, the coil terminals of adjacent electromagnetic blocks are disposed in a row at narrow pitch on only one side of the relay. This complicates the layout and wiring of a base.
Secondly, the electromagnetic blocks having the same shape occupy more space when oriented in line as described above. However, it is uneconomical to form the blocks into different shapes so as to efficiently utilize the space in that the respective blocks cannot be composed of uniform parts.
Thirdly, in the above patent application, the electromagnetic blocks are described as being joined, but there is no particular description of how to join the blocks. Assuming that the blocks are joined by using adhesive etc. (considering their shapes, it seems unlikely that the blocks are swaged or bolted together), dimensional distortion or deviation easily occurs. That is, the dimension of the coupled blocks may elongate in the arranging direction. In this case, the first and second stationary terminals, which are bent and formed to the proper dimensions for engagement with the coupled blocks to be fixed thereto, may be unable to accommodate accumulative deviations depending on the number of the blocks joined together. Consequently, it becomes impossible to attach the stationary terminals to the blocks. With this construction, the electromagnetic relay cannot be assembled precisely.
Fourthly, each stationary terminal is provided with a plurality of stationary contacts so that the electromagnetic blocks share the common stationary terminals. As a result, when a stationary contact comes in contact with a moving contact, vibrations set up at the stationary contact are propagated to every stationary contact of the same stationary terminal. That is, a contact on operation easily transmits vibrations to other contacts, which undermines contact reliability. Besides, since the electromagnetic blocks are disposed in side-by-side contacting relation, the electromagnetic relay is structurally liable to allow the propagation of vibrations.
Moreover, in this construction, exothermic heat evolved from passing current concentrates on the contact areas of the stationary terminals, and thus current-carrying performance is deteriorated.
It is therefore an object of the present invention to provide an electromagnetic relay apparatus, which is improved in size, performance, assembly accuracy, cost, productivity, and reliability.
In accordance with the first aspect of the present invention, to achieve the above objects, there is provided an electromagnetic relay apparatus comprising a plurality of electromagnetic relays each having dual or a couple of moving contacts that swing by the excitation current flow in a coil, a couple of stationary contacts set against the directions of movement of the moving contacts with the moving contacts between them, wherein one of the moving contacts and one of the stationary contacts form a normally open contact (NO contact) which is closed when excitation current is applied to the coil, the other moving contact and the other stationary contact form a normally closed contact (NC contact) which is closed when current is not passed through the coil, and the electromagnetic relays are disposed in line on a base so that the NO/NC contacts of adjacent electromagnetic relays are located in opposed outer positions in substantially point symmetrical relation.
In accordance with the second aspect of the present invention, in the first aspect, the electromagnetic relay has a first stationary terminal that is provided with a first stationary contact forming the NO contact and a second stationary terminal that is provided with a second stationary contact forming the NC contact separately, each being connectable to external wiring.
In accordance with the third aspect of the present invention, in the second aspect, the moving contacts swing upward and downward, and the first and second stationary terminals are set on the base so as to extend from opposite directions at right angles to the directions of movement of the moving contacts, with the first stationary contact being located under the moving contacts and the second stationary contact being located above the moving contacts.
In accordance with the fourth aspect of the present invention, in the third aspect, the electromagnetic relay comprises an electromagnetic block, the first stationary terminal of substantially L-shape having the first stationary contact, and the second stationary terminal of substantially L-shape having the second stationary contact. The electromagnetic block includes a couple of coil terminals, a coil assembly that is formed by winding coil wire connected with the coil terminals around a spool, a yoke of substantially L-shape mounting the coil assembly on its inner basal surface, a cylindrical core extending through the coil assembly to hold the assembly in place, and a moving terminal that is provided with a vertically movable armature extending from the top of the upstanding surface of the yoke over the coil assembly and the moving contacts on both surfaces at the end extending beyond the armature, and is fixed to the outer upstanding surface of the yoke. Besides, a plurality of stationary terminal holders of required height each having substantially an C-shape in a plan view are formed on the base with adjacent stationary terminal holders being located in diagonally opposite positions. The stationary terminal holder supports the first and second stationary terminals so that the terminals extend out from the opposite sides thereof toward each other with the first and second stationary contacts being located one above the other. The electromagnetic block is placed opposite the stationary terminal holder.
In accordance with the fifth aspect of the present invention, in the fourth aspect, the base is formed in a manner so as to have raised portions each forming the stationary terminal holder with adjacent raised portions being coupled at their respective edges of the C.
In accordance with the sixth aspect of the present invention, in the fourth aspect, the base is formed in a manner so as to have separate raised portions each forming the stationary terminal holder.
In accordance with the seventh aspect of the present invention, in the fifth or sixth aspect, a first fitting hole is formed at the lower midpoint of the concave surface of the stationary terminal holder, and the edge of the basal surface of the yoke is fitted in the first fitting hole to attach the electromagnetic block to the base.
In accordance with the eighth aspect of the present invention, in the fifth or sixth aspect, the yoke is formed integral with the base.
In accordance with the ninth aspect of the present invention, in the seventh or eighth aspect, a couple of second fitting holes are oppositely formed in the upper surface of the stationary terminal holder so that the first and second stationary terminals are fitted therein in the direction of downward movement of the moving contacts, and the first and second stationary terminals are fitted partway into the second fitting holes, respectively.
In accordance with the tenth aspect of the present invention, in the seventh or eighth aspect, the first stationary terminal is molded partway in the stationary terminal holder by insert molding, a third fitting hole is formed in the upper surface of the stationary terminal holder so that the second stationary terminal is fitted therein in the direction of downward movement of the moving contacts, and the second stationary terminal is fitted partway into the third fitting hole.
In accordance with the eleventh aspect of the present invention, in the ninth or tenth aspect, the base is molded.
In accordance with the twelfth aspect of the present invention, in the eleventh aspect, the main body of the electromagnetic relay apparatus composed of the electromagnetic relays and the base is provided with a closure cover having an opening in engagement with the base.
In accordance with the thirteenth aspect of the present invention, in the twelfth aspect, the cover is sealed to the main body of the electromagnetic relay apparatus with a thermosetting resin member.
In accordance with the fourteenth aspect of the present invention, in the thirteenth aspect, the electromagnetic relay apparatus comprises a couple of the electromagnetic relays.